Buoyant performance of U.S. tech stocks is driving some fund managers to dismiss longstanding valuation concerns as short-sighted

The buoyant performance of U.S. tech stocks is driving some fund managers and others to dismiss longstanding valuation concerns as short-sighted.

While shares of companies including Amazon.com Inc., Netflix Inc. and Salesforce.com Inc. have surged this year to price/earnings ratios that are several times the market’s longtime average, many fans of these investments contend that such metrics can overstate risks. They say they prefer a broader assessment of financial and strategic progress, arguing that this view can be more...